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Used MLS a few times. There were (don't know if they still exist) a few in the PNW. One had a 4.5 degree glideslope which made for a challenge especially if there was any tailwind.
Not every runway has an ILS. Even at major airports, not every runway has an ILS. There are several other types of instrument approaches. Some rely on technology from the 1930s, I believe (NDB Approaches). Some runways don't even have an instrument approach.
I agree that an ILS is a great aid. About 20 years ago there was a push to implement MLS (Microwave Landing Systems). Supposedly they were going to replace all other instrument approaches and be capable of accommodating all runways.
Yes, I understand that. But I think it can be safely said that the vast majority of runways handling a high volume of heavy jet landings does. The exceptions are few are far between.
All of SFO's runways (normally) have them, except for 19R, I believe....which is hardly ever used for landings.
Yes, I understand that. But I think it can be safely said that the vast majority of runways handling a high volume of heavy jet landings does. The exceptions are few are far between.
All of SFO's runways (normally) have them, except for 19R, I believe....which is hardly ever used for landings.
Runway 19 is used when the wind is from the south, and too strong for crosswind landings on runways 28. That condition usually occurs with a weather pattern that has strong rain showers and thunderstorms in the area. Under those conditions runway 19 is a challenging approach because you're landing in strong, usually gusty winds, on a wet runway only 7,500 feet in length. During my 20 years based in SFO, I landed on runway 19 only 3 times, and each time was a challenge.
At one time, approaches were allowed on runway 1, although they were very rare, but I don't see an approach for that runway now. It was a very interesting approach because on the downwind leg, you're heading south directly toward the mountain and as you get abeam the end of the runway, the terrain is sloping up steeply ahead of you. It's a close in, steep approach, not very high over all the homes in that area. It was more than challenging approach, and I'm sure the residents didn't appreciate the airplanes in such proximity to their homes.
The question is still WHY the aircraft got low and slow without early corrections, since there were three pilots in the cockpit.
What were they seeing outside?
What were their instruments indicating?
Was the actual weight of the aircraft heavier than they computed for their approach speeds, causing the wrong approach speed to be computed?
Were there instrument failures?
We don't know those answers, nor do we know the many other factors that may have contributed to the accident. That's why the experts know they can't call something pilot error until all of the data has been discovered and analyzed.
I'm going with the heavy theory, at least as part of the ultimate finding. But does that also explain the steep descent? I'm not familiar with the software.
I'm going with the heavy theory, at least as part of the ultimate finding. But does that also explain the steep descent? I'm not familiar with the software.
The aircraft weight wouldn't have anything to do with the steep descent.
Here's a page that shows the descent path compared to another flight the day before:
According to this graph, he was a little high at 3 minutes out, and that is no big deal. He apparently made a correction and was at the proper altitude for the distance from the runway at 1600 feet. That would have been fine had the descent rate been adjusted at that point.
However, it appears that adjustment of the descent rate to the (approximately) 3 degree glide path rate was not made, and the aircraft went below that glide path. It looks like the descent rate was adjusted at around 900 feet and he was on a normal 3 degree glide path rate. However, he was about 250 feet low, and didn't make a correction until it was too late.
Apparently, the problem(s) started around that point where they went below the normal (visual) glide path. And the big questions remain of what were they seeing in the cockpit instruments? Were they having some problems that took everyone's attention away from the actual flying of the aircraft? That shouldn't happen because if there are problems, the pilot flying continues to fly the aircraft and the other pilot(s) take care of the problem and still monitor the flight path to back up the pilot flying.
There remains the possibility that they thought the airplane was faster than it actually was; in other words, there could have been an instrument indication problem. I haven't ruled pilot error out, but I still need to have a lot more information because there can be many underlying, contributing factors that we are not aware of.
Hello Mike, a 7000 foot runway is no problem for a 747. I notice that I wrote 1500 feet is the target point. That was a typo. 1000 feet is the target point, and landing between the 500 and 1500 foot marker is the goal. The touch down zone is 3000 feet, and the aircraft must be landed within that area, or a go around should be executed. (That was our procedure. While you could safely stop on most runways if you landed at 4000 feet, if a brake malfunctioned after landing and you couldn't stop, then you could be cited by the company for landing long.)
The white arrows point to a horizontal white line followed by 12 vertical hash marks. The white line is the beginning of the runway, and one should never touch down before that point.
The next group of hash marks (6) 3 on each side of the center line is the 500 foot marker
The next marker is the 2 large squares, one on either side of center line. That is the 1000 foot marker, the target point.
Each group is spaced 500 feet apart, the next two groups have 2 hash marks on either side, and the following two groups have 1 hash mark on either side. The last mark is the 3000 foot marker.
The 747 in the photo appears to be going to touch down prior to reaching the beginning of the runway. He is flaring, but his main gear is about 500 feet from the beginning of the runway. At any rate, it was not safe being that low at that point. There was no reason for him to be that low. If he was trying to give the people on the beach a thrill, it was a poor judgement call.
Thanks for the clarification on the 1500-foot target point, Bill.
With St. Maarten, I'm sure smaller aircraft like the Boeing 737, 757, or the Airbus A320, would do okay past the 1500-foot marker, maybe up to the 2000-foot marker, but I wouldn't go past that, and I definitely wouldn't try it with a 747, not even the smaller 767, or the A330.
I'd still like to know what was going on in the flight deck of the Asiana Boeing 777 before they called for the go-around, and allowed the aircraft's air speed to be at a very low 103 knots. I can't understand how anyone in the flight deck didn't pay enough attention to one of the most important parameters in executing a successful landing of a heavy aircraft, the air speed, until they heard the stall warning, which could indicate, as you mentioned in your previous post, a possible instrument problem.
Last edited by Magnum Mike; 08-05-2013 at 03:04 PM..
There remains the possibility that they thought the airplane was faster than it actually was; in other words, there could have been an instrument indication problem. I haven't ruled pilot error out, but I still need to have a lot more information because there can be many underlying, contributing factors that we are not aware of.
I'm not going to say it's impossible but the likelihood that there was an indication problem is extremely unlikely. There are six sensors on the 777 aircraft being simultaneously monitored for their inputs (three pitot and three static) with the correct ones calculated and managed through a computerized redundancy management system while the incorrect ones are voted off the island. There is a backup in the form of a secondary air data unit also doing the same thing.
For example, let's say a dirt dobber builds a nest in the left pitot probe... The plane takes off... In the old days, the captain might see very erratic indications on his airspeed display. On the 777, the computer might see the following airspeeds (65, 272, 271). It'll basically boot out the value of 65 and take the mid-range average of 272, and 271. So, even if the left pitot probe is completely blocked off, the captain's airspeed would read normally with the maintenance computer logging a fault in the left probe. If two failures occur, the plane can still deduce which one is most accurate and continue on.
In the event of all out system failure, in the main computer and the one doing the backup calculations (the odds on this are astoundingly ridiculous), the aircraft then switches over to a single channel mode (no redundancy logic) and then computes the data based on the left side sensor inputs..
Any system that does fail would be readily retrievable by the maintenance computers and flight data recorders. To be quite honest, we'd have heard about it already if this didn't jive. There is just so much redundancy built into the airplane for the air data systems that we'd be hearing about it by now.
I believe this is going to come down to Crew Resource Management... Not a mechanical failure.
Location: About 10 miles north of Pittsburgh International
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If I were a betting man; if we had a pool going with all the possibilities, my money would be on one of my favorite aviation buzz phrases--primary/backup inversion. (Or some kissin cousin to it.)
This is based on what has been released, and lots of good information as well as speculation and opinions that I've read, here and elsewhere.
I think they didn't quite have a handle on what their systems were up to, and were expecting the autothrottles to keep track of the airspeed, and were rudely surprised when they found themselves out of airspeed, altitude, and ideas....
(Yeah, I know, I know, wait for the findings, and I'll be happy to admit it when I'm wrong....)
The first officer aboard Asiana Flight 214 told investigators that he called out the plane's excessive sink rate -- its rate of descent -- "more than four times" in the two minutes before the plane crashed, according to information released by the National Transportation Safety Board on Wednesday as it began a marathon 11-hour hearing into the July accident in San Francisco, which killed three Chinese teenagers.
This was interesting too:
Quote:
Bong said the crew practiced "cockpit resource management," training that encourages subordinates to speak up about safety concerns to other crew members, despite their senior rank, experience or seniority. But when the student captain was asked whether he had contemplated an aborted landing as the plane descended, Lee Kang K.uk [the post kept starring out his name] said it was a "very hard" decision to make, given the deference shown in Korean culture.
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